I have what i believe to be a tappy valve in my 1991 4Runner, V6. It's quiet when the engine is first started, before the oil is warm, presumably. Once the engine up to temp the tap comes back. Does that mean I should be using a heavier grade engine oil? The level is fine, it's not low or anything. It seems to me a thicker oil would maybe still be more effective even after warming up?
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You need to check your exhaust gaskets between the heads and exhaust manifolds. Many times when there's exhaust leaks there, it will make the sounds like you described (quiet at first startup and noise once warmed up). The puffs of exhaust can sound just like valvetrain noise, or even in some cases like a rod knock. Before you go worrying about oil, make sure you check here first.– Pᴀᴜʟsᴛᴇʀ2 ♦Oct 17, 2019 at 17:13
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i saw that mentioned somewhere else, wasn't sure what to make of it. I'll investigate. But it definitely tracks with oil temp/pressure; i should have mentioned the pressure, really. The gauge starts out high/normal when cold, then as it warms up it drops down a lot so that it sits at around the 1/4 mark on the scale. It's visual and right in my face, that's probably why i keep thinking oil. Thanks a lot.– tntwyckoffOct 17, 2019 at 20:11
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It isn't like your 4Runner is a spring chicken, so I could see either being the case.– Pᴀᴜʟsᴛᴇʀ2 ♦Oct 17, 2019 at 20:20
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just went through a stack of receipts from the prev owner, they had the head gasket done, the heads re-surfaced, and the valves adjusted pretty recently, actually. makes the case for the exhaust as the source.– tntwyckoffOct 17, 2019 at 21:03
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